Inorganic fiber mats (hereinafter, they may be referred to simply as mats) made of inorganic fibers such as glass wool, rock wool or the like have widely been used as a heat insulating/sound absorbing material for, e.g., houses. It is known that the entire surface of an inorganic fiber mat is covered with resin films when the mat is used as a heat insulting/sound absorbing material, in order to eliminate an irritating feeling to workers due to the dispersion of inorganic fibers broken off by handling during transportation, construction or the like, and to protect the inorganic fiber mat from moisture.
The heat insulating/sound absorbing material is produced by supplying inorganic fiber mats each cut to have a predetermined size to a band-shaped continuous resin film with a predetermined space between the mats, covering the front and the rear surfaces and both side surfaces along the longer sides of the mats, and cutting the resin films at portions between the mats to cover both side surfaces along shorter sides of the mats with the resin films.
Namely, for example, JP-A-09-156003 discloses a process for producing a heat insulating/sound absorbing material, comprising covering inorganic fiber mats each cut to have a predetermined size with a single or two band-shaped resin films in a manner that a predetermined space is provided between the mats, bonding the resin films at their bonding surfaces along the longer sides of the inorganic fiber mats, and cutting the resin films at portions between the mats by a cutting apparatus.
Also, the JP-A-09-156003 discloses specifically a cutting apparatus for the process. The cutting apparatus has the substantially same principle as the cutting apparatus of the present invention shown in FIG. 3 in that the resin films are cut in a pressed state. Namely, the cutting apparatus comprises a cutting blade disposed between two conveyors for conveying organic fiber mats covered with resin films, and perpendicularly to a conveying line of these conveyors, and a pair of pressing plates disposed at both sides of the cutting blade. Further, at underneath positions corresponding to the pair of pressing plate, a pair of receiving plates are disposed, whereby the resin films are cut at portions between the mats by moving the cutting blade down in a state that the resin film are pressed against the receiving plates by the pressing plates.
However, since a pressing plate 7 of the conventional cutting apparatus has a flat bottom surface as shown in FIG. 12, when the pressing plate 7 is moved down to press the resin films against a receiving plate 7, portions to be cut of the resin films are uniformly pushed by the flat bottom surface of the pressing plate. On the other hand, since both side fringes of the front side film 6a are bonded to the rear side film 6b by an adhesive 8, and air is included in the space enclosed by the front side film 6a and the rear side film 6b, both ear portions of the front side film 6a are pushed out sideways as shown in FIG. 12, when the front side film 6a is pressed by the pressing plate 7. When the films are further pressed by the pressing plate 7, the ear portions of the front side film 6a are further spread to finally be in a state as shown by the chain double-dashed lines, and may protrude outwardly from the extensions 14 of the rear side resin film at longer sides of the heat insulating/sound absorbing material. The front side film 6a and the rear side film 6b are cut by the cutting blade in this state, and at the same time, extensions of the front side film 6a and the rear side film 6b are bonded with an adhesive 8.
Accordingly, distortions 12 are formed at the ear portions of the extensions 15 of the resin films at shorter sides of the cut heat insulating/sound absorbing material. The distortions 12 become larger as the inorganic fiber mat is thicker, and may extend to the outside of the extensions 14 of the rear side film 6b. Accordingly, a conventional resin film covered heat insulating/sound absorbing material has not only a problem that its external appearance is bad, but also a problem in that the distortions 12 become obstacles when the heat insulating/sound absorbing material is inserted into a gap or space between columns of a building and the workability of the construction is thereby deteriorated.
Further, in order to improve the productivity, resin film covered heat insulating/sound absorbing material is generally produced so that an inorganic fiber mat having a large width and formed by collecting fibers, is cut along a longitudinal direction at first as illustrated in FIG. 14 to be divided in the width direction into, for example, three strips, the mat strips arranged in three rows are cut along cutting lines 13 to have a predetermined size in order to cover six surfaces of each mat with resin films and, three rows of the mats thus produced are arranged and covered with resin films 6. Heretofore, the apparatus is so constructed that the resin films covering the plurality of the rows of the mats are cut by a single cutting blade all at once, whereby the cutting can be performed even if distortion of the resin films of neighboring rows are overlapped.
However, since movements of inorganic fiber mats in the plurality of rows are irregular, displacements may be caused. Accordingly, although the resin film can be cut at a predetermined interval, the mats are often cut when the displacement is large. On the other hand, if the cutting apparatus for cutting the resin films is provided for each of the rows, and if the length of the cutting blade is increased considering the margin for the distortion, the spacing between the rows needs to be increased, and the width of the conventional producing apparatus is thereby increased.
The present invention has been made considering the above problems, and it is an object of the present invention to provide a heat insulating/sound absorbing material having no distortion that becomes obstacle at cutting portions of the resin films, a process and an apparatus for producing it.